This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. An ongoing project aimed at confirming, with MALDI-MS, the identification of various proteins involved in DNA replication. These proteins are being overexpressed and reconstituted for the purpose of X-Ray crystallographic determination of their three-dimensional structures. MCM proteins from S. cerevisiae and B. subtilus, and ORC proteins from S. cerevisiae are among the protein complexes under study.